A camera module has been mounted in various electronic devices such as a mobile phone and a smartphone. Examples of camera modules encompass (i) a conventional camera module in which (a) no lens driving device is included and (b) a lens is held only by a holder and (ii) a camera module which uses a lens driving device to carry out an automatic focusing function and a camera shake correction function. These camera modules have been already distributed to the market. Examples of lens driving devices, i.e., actuators, encompass various types, such as a stepping motor, a piezoelectric element, and a VCM (Voice Coil Motor), and these lens driving devices have been already distributed to the market. Although the market has a strong demand for a reduction in size of the camera module, a structure of the camera module has become complicated, and thus a higher accuracy is required for positioning a lens with respect to an imaging element.
A camera module is usually produced in such a manner that while a lens section, in which a lens unit is incorporated into an actuator unit in advance, is being aligned with a sensor section in which members such as a sensor chip, a wire, a cover glass, and a sensor cover are incorporated into a substrate, the lens section is bonded to the sensor section by use of an adhesive resin.
Many methods are proposed for the above alignment. For example, a method similar to the one shown in FIGS. 23 and 24 is known. According to the method, a lens section is illuminated by a ring illumination device 117 from a back surface side of the lens section, while being vacuum-sucked by a suction head 114. Further, an image recognition camera unit 116 carries out image recognition of each of (i) an edge 103e of a lens barrel 103 and (ii) an edge 102e of a retainer 102. While the lens section is being aligned with an effective pixel area of an imaging sensor chip with respect to which effective pixel area image recognition has been carried out in a manner similar to the above image recognition, the lens section is mounted, by a device, on a sensor section to which an adhesive resin has been applied in advance.
Patent Literature 1 also discloses a method of carrying out the above alignment. Patent Literature 1 discloses an electronic part mounting device for mounting, on a circuit substrate (not illustrated), an electronic part 203 illustrated in FIG. 25. The electronic part mounting device 220 includes (i) support columns 221a and 221b which are integrated with a head unit and (ii) a CCD camera 222 which (a) is provided at an end part of the support column 221a and (b) captures, from obliquely below, an image of an image-captured surface of the electronic part 203 opposite to an adhesion surface, adhered by an adhesion nozzle support column 212, of the electronic part 203. The electronic part mounting device 220 further includes an illumination device 223 which (i) is provided at an end part of the support column 221b and (ii) illuminates a bottom surface, adhered by the adhesion nozzle support column 212, of the electronic part 203. In this case, the illumination device 223 irradiates the electronic part 203 with light from obliquely below, specifically, from a position linearly symmetric to the CCD camera 222 with respect to an axis of an adhesion head 212a. A reference sign 224 indicates a course of light emitted from the illumination device 223. The CCD camera 222 receives light reflected from the bottom surface of the electronic part 203. An image captured by the CCD camera 222 is processed. An edge point in the image is then extracted so as to generate an edge image. An outer edge part of the electronic part 203 is then determined on the basis of the edge image thus generated, so as to check for a positional displacement.
On the other hand, Patent Literature 2 discloses a technique for carrying out a tilt correction by use of parts which are in contact and are engaged with each other.